1. Field of the Invention
This invention relates to suction accumulators for use in conjunction with vapor compression heat transfer systems such as air conditioning systems and heat pumps. This invention also relates to suction line filter-driers for use in conjunction with such vapor compression heat transfer systems.
2. Description of the Background Art
Conventional vapor compression heat transfer systems comprise a compressor, condenser, throttling device, and evaporator connected in serial fluid communication with one another. The system is charged with a refrigerant which circulates through each of the components to remove heat from the evaporator and transfers such heat to the condenser. During operation, the compressor compresses the refrigerant from a saturated-vapor state to a super-heated vapor state thereby increasing the temperature, enthalpy, and pressure of the refrigerant. The refrigerant then flows through the condenser which condenses the refrigerant at a substantially constant pressure to a saturated-liquid state. The throttling device reduces the pressure of the refrigerant thereby causing the refrigerant to change to a mixed liquid-vapor state. The refrigerant then flows through the evaporator which causes the refrigerant to return at a constant pressure to its saturated-vapor thereby completing the thermal transfer cycle.
It has been long recognized, under some operating conditions, that the evaporator may not sufficiently function to completely evaporate the liquid refrigerant following from the condenser. When incomplete evaporation occurs, liquid refrigerant flows into the compressor and causes great damage to the compressor. Devices, generally known as suction accumulators or surge drums, have been developed to prevent such liquid floodback of the refrigerant to the compressor, and are used in conjunction with virtually all systems employing flooded-type evaporators. One of the most widely used accumulators basically consists of a cylindrical shell having an inlet positioned in the upper portion of the shell and connected to the suction line from the evaporator. The outlet is connected to an upstanding U-shaped tube internal to the shell and is connected to the suction line to the compressor. During use, the refrigerant flows into the shell via the inlet and, because of the upstanding U-shaped tube, only vaporized refrigerant is allowed to flow via the tube and outlet to the compressor. All of the liquid refrigerant is consequently accumulated in the bottommost portion of the shell. U.S. Pat. Nos. 3,084,523, 3,212,289, 3,344,506, 3,420,071, 3,432,910, 3,443,367, 3,589,395, 3,643,465, 3,837,177 and 3,872,689, the disclosures of each of which are hereby incorporated by reference herein, illustrate various embodiments of conventional suction accumulators.
It has also been long recognized that moisture and other impurities may enter the heat transfer system when the circuit is opened for repair or maintenance. Suction line filter-driers have been developed to be connected in the suction line of the system to remove such moisture and other impurities. Conventional filter-driers consist of a shell having an inlet and an outlet. A desiccant, such as moisture-absorbing silica gel, and a screen are positioned within the shell to remove the moisture and particulate impurities from the refrigerant as the refrigerant flows through the filter-drier and before the refrigerant enters the compressor. After the moisture and other impurities have been dried and filtered from the refrigerant gas, the filter-drier has served its purpose and should be removed from the system. Unfortunately, the sealed type of filter-drier cannot be removed from the suction line without cutting into the system and, again, exposing it to moisture and other contaminates. Consequently, the sealed type filter-driers are usually left in the system even after they have accomplished their intended purpose.
Replaceable core type filter-driers have recently been developed which allow the removal of the filter elements from the shell after the refrigerant has been sufficiently filtered and dried. These replaceable core filter-driers typically comprise a shell in which are positioned one or more filter elements. Access is provided to the shell by means of a flange cover bolted to a flange integral with the shell itself. A more detailed description of these replaceable core filter-driers can be found in Bulletin 14.50T published September, 1974 by the ALCO Controls Division of Emerson Electric Company, St. Louis, Mo. and by Bulletin 40-10, published in December, 1978 by Sporlan Valve Company, St. Louis, Mo., the disclosures of each of which are hereby incorporated by reference herein.
It is apparent that both the suction accumulator devices and the filter-drier devices perform extremely useful functions in connection with vapor cycle heat transfer systems. However, the need for two seperate devices significantly adds to the overall cost of the system because of the cost of the devices themselves, and the labor and materials costs in installing each of the devices in the system.
Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the suction accumulator and suction filter-drier arts.
Another object of this invention is to provide a device which functions as a suction line filter-drier to remove moisture and other contaminates from refrigerant flowing through the circuit of a vapor compression heat transfer system.
Another object of this invention is to provide a device for preventing liquid refrigerant from flowing into the compressor of a vapor compression heat transfer system.
Another object of this invention is to provide a device which functions as a suction line filter-drier which may be conveniently interchanged to function as a suction line accumulator.
Another object of this invention is to provide an interchangeable suction line accumulator and filter-drier which is economical to manufacture and easily installed in new and existing vapor compression heat transfer systems.
Another object of this invention is to provide an interchangeable suction line filter-drier and accumulator which utilizes commercially available filter-drier blocks or cores having desiccant properties to remove moisture from the system and filter properties to remove impurities from the refrigerant such as dirt, acids, sludge and varnish.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.